The concept of foldability and/or collapsibility for various articles such as chairs, benches, tables and golf carts has long since been known. Articles of the type just mentioned can be relatively bulky and space-consuming when in the erected utility condition; therefore, it is desirable to collapse or fold the article into a low volume condition for transportation and storage.
Perhaps no article of furniture has received more attention in terms of designing collapsibility or foldability than the chair. Perhaps the best known example is the so-called card table chair in which the seat typically pivots into alignment with the backrest and the forward legs simultaneously move closer to the rear legs.
Two folding chairs which are more relevant to the present invention and which merit comparison for purposes of understanding both the structure and the advantages of the present invention are disclosed in the U.S. Pat. Nos. to Rohr 4,047,752 and Lee No. 4,605,261. Both Rohr and Lee disclose chairs which, in overall concept, are excellent. However, the implementation of the concept in each case creates certain disadvantages.
Both the Rohr and Lee chairs may be characterized as comprising a collapsible tubular metal frame and a fabric or fabric like integral seat and back portion which is easily attached to and removed from the frame at the rear top edge and the front right and left corners of the fabric element. Both the Rohr and Lee frames comprise a front or forward multiple joint member or "spider" for receiving foldable left and right front legs and left and right front seat edge support struts. In addition both Rohr and Lee include as part of their frame a rear foot which is connected to the front joint member by means of a longitudinal strut and which rests upon the ground. Extending rearwardly and upwardly from the foot is a back support strut which is adjustable in length and, at least in Rohr's case, inclination. An obvious disadvantage of the Rohr is the lack of lateral support at the rear foot, giving rise to a relatively unstable or "tippy" chair. Lee appears to solve this problem by providing outboard leg struts attached to the foot. The two chairs are otherwise remarkably similar.
Both the Rohr and Lee chairs exhibit a further disadvantage in the structure of the pivotal connection between the various strut members and the spiders or joints. Rohr is typical in disclosing a telescopic relationship between an outside tube portion of the joint and an inside tubular strut which fits into the outside tubular structure of the joint. The inside tube is stopped against a crosspin which also provides the anchor joint for a wire and spring combination which extends up into the tubular strut and is anchored some distance into the strut by means of a second pin. Accordingly the spring holds the inside strut tube into the outside spider tube when the leg or strut is in the erected condition but permits the inside strut to be pulled out of the outside tube and folded to one side when one desires to collapse the chair.
The Rohr chair lacks stability in the folded condition since the connecting wire 38 lies between the two disconnected tubes and essentially prevents the anchoring of the disconnected strut in any sort of stable position. Moreover the seating of the end of the inside tube against the crosspin 40 will tend to deform the inside tube, especially if it is made of a lighter material such as aluminum. Finally, the use of the crosspin 41 to anchor the spring within the tube of the strut member gives rise to assembly difficulties and requires that the feet and other terminal members of the outwardly extending struts be more or less permanently attached.
Lee suffers from the same disadvantage as far as the anchoring of the tension springs is concerned and therefore suffers the same disadvantage in the assembly operation. Moreover Lee appears to disclose an unnecessarily complicated structure at the joint.